From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f170.google.com (mail-we0-f170.google.com [74.125.82.170]) by kanga.kvack.org (Postfix) with ESMTP id 34FA56B006E for ; Fri, 9 Jan 2015 06:06:11 -0500 (EST) Received: by mail-we0-f170.google.com with SMTP id w61so7264267wes.1 for ; Fri, 09 Jan 2015 03:06:10 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id w7si19746674wiz.10.2015.01.09.03.06.09 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 09 Jan 2015 03:06:09 -0800 (PST) From: Michal Hocko Subject: [PATCH -v3 2/5] oom: thaw the OOM victim if it is frozen Date: Fri, 9 Jan 2015 12:05:52 +0100 Message-Id: <1420801555-22659-3-git-send-email-mhocko@suse.cz> In-Reply-To: <1420801555-22659-1-git-send-email-mhocko@suse.cz> References: <1420801555-22659-1-git-send-email-mhocko@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Tejun Heo , "\\\"Rafael J. Wysocki\\\"" , David Rientjes , Johannes Weiner , Oleg Nesterov , Cong Wang , linux-mm@kvack.org, LKML , linux-pm@vger.kernel.org oom_kill_process only sets TIF_MEMDIE flag and sends a signal to the victim. This is basically noop when the task is frozen though because the task sleeps in the uninterruptible sleep. The victim is eventually thawed later when oom_scan_process_thread meets the task again in a later OOM invocation so the OOM killer doesn't live lock. But this is less than optimal. Let's add __thaw_task into mark_tsk_oom_victim after we set TIF_MEMDIE to the victim. We are not checking whether the task is frozen because that would be racy and __thaw_task does that already. oom_scan_process_thread doesn't need to care about freezer anymore as TIF_MEMDIE and freezer are excluded completely now. Signed-off-by: Michal Hocko --- mm/oom_kill.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 80b34e285f96..3cbd76b8c13b 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -266,8 +266,6 @@ enum oom_scan_t oom_scan_process_thread(struct task_struct *task, * Don't allow any other task to have access to the reserves. */ if (test_tsk_thread_flag(task, TIF_MEMDIE)) { - if (unlikely(frozen(task))) - __thaw_task(task); if (!force_kill) return OOM_SCAN_ABORT; } @@ -423,6 +421,14 @@ void note_oom_kill(void) void mark_tsk_oom_victim(struct task_struct *tsk) { set_tsk_thread_flag(tsk, TIF_MEMDIE); + + /* + * Make sure that the task is woken up from uninterruptible sleep + * if it is frozen because OOM killer wouldn't be able to free + * any memory and livelock. freezing_slow_path will tell the freezer + * that TIF_MEMDIE tasks should be ignored. + */ + __thaw_task(tsk); } /** -- 2.1.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org